BRaaS-HPC-HayStack Composer

A Blender addon that provides a node-based visual interface for composing and generating HayStack rendering commands. This addon enables users to create complex scientific visualization workflows through an intuitive node editor.

Overview

BRaaS-HPC-HayStack Composer is a Blender addon developed by IT4Innovations National Supercomputing Center for creating HayStack rendering pipelines. It allows users to visually compose rendering commands through a node-based interface, supporting various data formats including unstructured meshes, volumes, point clouds, and more.

The addon generates executable command-line instructions that can be run locally or on remote HPC clusters via the BRaaS-HPC infrastructure.

Features

• Visual Node-Based Workflow: Create rendering pipelines by connecting nodes in Blender's node editor
• Multiple Data Loaders: Support for various scientific data formats (UMesh, OBJ, Mini, Spheres, NanoVDB, RAW volumes, etc.)
• Render Backends: Multiple rendering targets including BRaaS-HPC, hsViewer, hsViewerQT, and offline rendering
• Auto-Generate Code: Automatically generate command-line code as you modify node parameters
• Remote/Local Support: Work with both local files and remote HPC filesystem paths
• Transfer Function Editor: Create and manage volume transfer functions using Blender's material nodes
• Camera Control: Integrated camera setup with Blender camera objects

Requirements

• Blender: Version 4.5.0 or higher
• Optional: BRaaS-HPC addon for remote cluster execution

Installation

1. Download or clone the addon to your local machine
2. Open Blender
3. Go to Edit → Preferences → Add-ons
4. Click Install... button
5. Navigate to the addon folder and select the folder or zip file
6. Enable the addon by checking the box next to "BRaaS-HPC-HayStackComposer"

How to Use

Getting Started

1. Open Node Editor:

   • In Blender, switch any area to Node Editor (Shift+F3)
   • From the node editor header, select HayStack Composer from the tree type dropdown

2. Access the Panel:

   • In the Node Editor, press N to open the sidebar
   • Navigate to the HAYSTACK tab to find the composer panel

Creating a Basic Rendering Pipeline

Step 1: Add Data Loader Nodes

• Press Shift+A in the node editor
• Navigate to Add → DataLoader category
• Select a data loader node (e.g., UMesh, OBJ, RAWVolume, etc.)
• Configure the file path to your data file

Step 2: Add Scene Nodes (Optional)

• Add a Camera node from the Scene category
• Configure camera position, view direction, and field of view
• Add a TransferFunction node for volume rendering
• Create and configure a material for the transfer function

Step 3: Add Property Nodes (Optional)

• Add a Properties node to configure rendering parameters:
  • Number of frames
  • Paths per pixel (sampling rate)
  • Default radius for primitives
  • Merge options
• Add an OutputImage node to specify output path and resolution

Step 4: Add Render Output Node

• Add a render node from the Output category:
  • hsBlender(BRaaS-HPC): Render on remote HPC cluster
  • hsViewer: Interactive local viewer
  • hsViewerQT: Qt-based interactive viewer
  • hsOffline: Offline batch rendering

Step 5: Connect Nodes

• Connect data loader outputs to the render node input
• Connect camera and other scene nodes to the render node
• The render node can accept multiple inputs (up to 100 connections)

Step 6: Generate Command

• Click Generate Tree Code button in the HAYSTACK panel
• The generated command will be saved in a Blender text block
• Access it from the Text Editor in Blender

Auto-Generate Mode

Enable automatic code generation for real-time feedback:

1. In the HAYSTACK panel, check Auto Generate Node Code
2. Adjust the FPS slider to control update frequency (1-30 FPS)
3. Select any node in the tree
4. As you modify node parameters, code is automatically generated
5. The generated code appears in a text block named {TreeName}_command_node.cmd

Working with Remote Files

If you have the BRaaS-HPC addon installed:

1. Go to Edit → Preferences → Add-ons
2. Find BRaaS-HPC-HayStackComposer settings
3. Enable Remote/Local toggle for remote file access
4. In the Node Editor sidebar, use the Remote panel to browse remote filesystems
5. Navigate directories and select files directly from the HPC cluster

GUI Components

Node Editor Interface

HAYSTACK Panel (Sidebar → HAYSTACK tab):

• Generate Tree Code: Creates full command from entire node tree
• Auto Generate Node Code FPS: Sets refresh rate for auto-generation
• Auto Generate Node Code: Toggle automatic code generation
• Generate Node Code: Generate code for currently selected node only
• Active Node: Displays currently selected node name

Remote Panel (when remote mode enabled):

• Remote path: Current path on remote filesystem
• File browser: Navigate and select files from HPC cluster

Node Categories

DataLoader Nodes

• UMesh: Unstructured mesh files (.umesh)
• OBJ: Wavefront OBJ mesh files
• Mini: Mini mesh format files
• Spheres: Raw sphere data with configurable format and radius
• TSTri: Tim Sandstrom triangle files
• NanoVDB: NanoVDB volume files with optional spacing
• RAWVolume: Raw volume data with format, dimensions, and channels
• Boxes: Raw box primitive data
• Cylinders: Raw cylinder primitive data
• SpatiallyPartitionedUMesh: Spatially partitioned unstructured meshes

Scene Nodes

• Camera: Define camera position, view direction, up vector, and field of view
• TransferFunction: Volume transfer function using Blender materials

Property Nodes

• Properties: Configure rendering parameters
  • Num. frames: Accumulation frames
  • Paths per pixel: Sampling rate
  • Merge umeshes: Merge multiple unstructured meshes
  • Default Radius: Default sphere/cylinder radius
  • Measure: Enable performance measurement
  • ndg: Number of data groups
  • dpr: Data groups per rank
  • Head node: Enable head node creation
• Output Image: Specify output filename, directory, and resolution

Output Nodes

• hsBlender(BRaaS-HPC): Render on HPC cluster with hostname and port
• hsViewer: Interactive viewer
• hsViewerQT: Qt-based interactive viewer
• hsOffline: Offline rendering

Node Socket Types

• Orange sockets: HayStack command/data flow connections

Example Workflow

Volume Rendering Example

1. Add RAWVolume node

   • Set file path to your .raw volume file
   • Configure format (e.g., float)
   • Set dimensions (e.g., 512, 512, 512)
   • Set channels (e.g., 1)

2. Add Camera node

   • Set camera position (vp)
   • Set view direction (vi)
   • Adjust field of view (fovy)

3. Add TransferFunction node

   • Click "Create Material" to generate a transfer function material
   • Edit the color ramp and opacity curve in the material editor
   • Specify output .xf filename

4. Add OutputImage node

   • Set output filename (e.g., "render.png")
   • Set output directory
   • Set resolution (e.g., 1920, 1080)

5. Add Properties node

   • Set paths per pixel (e.g., 16 for better quality)
   • Set num. frames for accumulation

6. Add hsViewer or hsBlender(BRaaS-HPC) node

   • Set executable path
   • For BRaaS-HPC: configure hostname and port

7. Connect all nodes to the render node input

8. Click "Generate Tree Code" to create the command

Generated Command Structure

The addon generates command-line arguments that follow this general structure:

<executable_path> <data_files> --camera <vp> <vi> <vu> -fovy <angle> -xf <transfer_function> -o <output_path> -res <width> <height> --num-frames <frames> --paths-per-pixel <spp> [additional_options]

License

This software is licensed under the terms of the GNU General Public License.

Acknowledgement

This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ (ID:90254).